GRAPTOLITES. 97 
sides concave between the stipes, and the angles extended upon the mar- 
gin of the stipes. Stipes robust, equal, linear, elongate, proceeding in 
right lines from the centre. 
Within the disc or near it the stipes measure five hundredths of an 
inch in width; and beyond this the width, including the serrature, is thir- 
teen hundredths of an inch. Test thick: the common body occupies 
sometimes about one third of the entire width. Cellules long, strongly 
curved, the breadth at the aperture three or four times as great as at the 
base ; length a little more than three times the width at the aperture ; 
making an angle with the axis of 20° near the base of the cell, and from 
52° to 50° near the aperture. Margin of the aperture nearly straight, 
making an angle with the axis of 105°; and sometimes, when compressed, 
still greater. Denticles obtuse, about nineteen or twenty in the space of 
an inch. 
This species is remarkable for its extremely elongate stipes and strong 
central disc. Some of the largest individuals, with the stipes expanded, 
have extended over an area of at least sixteen inches in diameter. The 
stipes are extremely robust, and in their original state appear to have 
been quadrangular ; the measurement across the back of the stipe, when 
flattened, being seven ninths as great as the lateral measurement of the 
flattened stipe below the cell-denticles. The size of the stipes is not 
greater than in G. Headi; but these have a more rigid aspect, and are 
readily distinguishable when the cellules or cell-denticles can be seen. 
All the specimens, with one exception, present the exterior or non-cel- 
luliferous side at the base; the disc and stipes adhering to the stone on the 
celluliferous face; so that it is only towards the extremities of the 
branches, where they are turned on one side, that the full width or form of 
the cellules can be seen. An impression of ashort fragment of the cellulifer- 
ous surface of one of the stipes shows strong deep indentations. The cel- 
lules vary but little in their distance or approximation, from seventeen to 
twenty in the space of an inch being the extremes of variation observed. 
The disc is not uniform in its proportions, nor regular in form, nor does it 
always appear to bear the same proportion to the strength of the stipes; it 
has sometimes a very symmetrical octagonal form: its substance is often con- 
siderably thickened and striated parallel to the margins, which are thinner, 
attenuating from the centre. The cellules are subject to variation from 
the direction in which the stipes have been compressed, and in this respect 
show a greater variety of appearances than any other species in the col- 
lection. 
This species exhibits some differences in its mode of growth, and the num- 
ber of stipes is not invariable. One specimen presents but seven stipes ; the 
centre, funicle, and divisions on one side being of the normal character, 
while on the other, one division of the funicle does not bifurcate, but 
